The development of functional forebrain cholinergic systems that modulate behavior will be studied in rats. An anticholinergic drug, scopolamine, will be administered both intracerebrally and subcutaneously to rats at 2, 4, 8, 12, 16 and 20 days of age, and motor response measured. Current literature states that cholinergic systems are not functional until 20 days of age. However, pilot data indicate that behavioral responses can be elicited by scopolamine using either route of administration under certain environmental conditions but not others. The proposed experiments will extend the pilot data, and examine the possibility that warm temperature and light suppress scopolamine-induced behaviors.